Get same bump from a photo to a model
I'm not familiar with Marmoset Toolbag, so I can't speak for that part. But there should be a setting in there somewhere that you can adjust the strength of your bump map. It is the settings in your 3rd screenshot I believe.

In blender it works like this at least, notice the first image has a high strength on the clouds, the second has a lowered value for the clouds.



I don't believe this is a question related to Blender however since you use a 3rd party renderer, and it's the renderer that handles bump maps and such.

Hope this helps.